21724445635513 has 2 divisors, whose sum is σ = 21724445635514. Its totient is φ = 21724445635512.

The previous prime is 21724445635439. The next prime is 21724445635531. The reversal of 21724445635513 is 31553654442712.

It is a happy number.

Together with next prime (21724445635531) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20788830513529 + 935615121984 = 4559477^2 + 967272^2 .

It is a cyclic number.

It is not a de Polignac number, because 21724445635513 - 2²⁵ = 21724412081081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21724445635213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10862222817756 + 10862222817757.

It is an arithmetic number, because the mean of its divisors is an integer number (10862222817757).

Almost surely, 2^{21724445635513} is an apocalyptic number.

It is an amenable number.

21724445635513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21724445635513 is an equidigital number, since it uses as much as digits as its factorization.

21724445635513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096000, while the sum is 52.

The spelling of 21724445635513 in words is "twenty-one trillion, seven hundred twenty-four billion, four hundred forty-five million, six hundred thirty-five thousand, five hundred thirteen".